Rotary sewing-machine with chain-stitch attachment.



R. K. HOHMANN. ROTARY SEWING MACHINE WITH CHAIN STITCH ATTACHMENT.

APPLICATION FILED MAY 5A 1913. l 090, l 51 Patented Mar. l?, 1914.

4 SHEETS-SHEET 1.

R. K HOHMANN. ROTARY SEWING MACHINFJ WITH CHAIN STITCH ATTACHMENT.

' APPLIUATION FILED MAY 5, 1913. m LQL Patented Mar. 1f, 1914.

4 SHEETS-SHEET 2.

R. K. HOHMANN. BOTANY SEWING MACHINE WITH CHAIN STITCH ATTACHMENT.

APPLICATION FILED MAY 5, 1913. 1,09@,151 Patented Mar. 17, 1914.

4 SHEETS-SHEET 3.

4f T56/ g5) R. K. HOHMANN. ROTARY SEWING MACHINE WITH CHAIN STITCH ATTACHMENT.

APPLIATION FILED MAY 6, 1913. l .@9@ l 5 l Patented Mal'. 17, 1914.

4 SHEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

RICHARD K. HOHMANN, OF BELVIDERE, ILLINOIS, ASISIGNOR TO NATIONAL SEWING MACHINE COMPANY, OF BELVIDERE, ILLINOIS, A CORPORATION OF ILLINOIS.

ROTARY SEWING-MACHINE WITH CHAIN -STITCH ATTACHMENT.

Specification of Letters Patent.

Patented Mar. 17, 1914.

Application led May 5, 1913. Serial No. 765,416.

To all whom it may concern Be it known that I, RICHARD K. Hon- MANN, a citizen of the United States, and resident of Belvidere, county of Boone, State of Illinois, have invented certain new and useful Improvements in Rotary Sewing- Machines with Chain-Stitch Attachments, of which the following is a specification.

This invention has particular reference to an arrangement bywhich a lock stitch sewing machine can be made to produce a chain stitch.

While some of the features of my invention are applicable to different forms of sewing machines, I have shown the invention applied to a rotary hook machine in which the hook makes two revolutions for each reciprocation of the needle and some of the features of my invention are especially adapted for this type of machine.

The novel features of the invention will be apparent from the following description taken in connection with the accompanying drawings.

In the drawings, Figure 1 is a vertical longitudinal section of the machine embodying my invention. Fig. 2 is a bottom plan view; Fig. 3 is a vertical cross section on the line 3-3 of Fig. 1; Fig. 4 is a detail perspective view of the loop holder and operating means for `use in forming the cham stitch; and Figs. 5, 6, 7 and 8 are detail views showing the position of the thread in the various stages of the operation in formin the chain stitch.

As s own in these drawings my invention is applied to a sewing machine having the work-plate 1 and the upright column 2 and horizontal arm 3 carrying the working parts above the table. The head f1 is earried on the end of the horizontal arm 3 and it carries the needle bar 5 and presser foot bar 6. Shaft 7 is mounted in bearings in the horizontal arm being driven by any suitable means through the pulley 8 and operating the needle bar and take-up 9 in any usual way. The shaft 7 has a bevel gear 10 which meshes with the bevel gear 11 on the vertical shaft 12 mounted in bearings in the column 2 and this shaft 12 has at its lower end a bevel gear 13 meshing with the bevel gear 11 on the rotary shaft 15 below the workplate. The shaft 15 carries on its forward end a rotary hook 1G which in forming the lock stitch is adapted to engage the loop,

'spreadit and carry it around the lower spool holder 17. The gears 13 and 14: are so proportioned that the shaft 15 will make two revolutions for each revolution of the shaft 7 and thus the rotary hook will make two revolutions each time that the needle is reciprocated.

The above-described elements constitute no part of the invention claimed in the present casca-but the present invention consists in certain added mechanism combined with what has been described.

In order to use the mechanism to make a chain stitch I make use of a loop holder 18 which occupies a position immediately below the work-plate 1 and above the rotary hook 1G. lhis loop holder is adapted to reciprocate moving forward to make a portion of it enter the loop which is spread by the rotary hook or other loop spreading means below the plate. The holder is furthermore so constructed that when the loop is drawn tup it will be retained by the holder and so spread that the next loop of thread formed when the needle again descends can enter through it and thus the second loop will be interlocked with the first in the form of a chain stitch. In the particular form shown the holder 18 is carried by an arm 19 secured to a bushing 20 which surrounds and forms a bearing for the shaft 15. The bushing 20 has secured to its opposite end a member 21 having parallel arms 22, 23, which engage the slide block 21. This slide block 24 has an opening in it in which fits the rounded end of the lever 25. The lever 25 has a bearing 2G fitting the bearing in 27', whereby it may turn or oscillate. 'l` e lever 25 at its opposite end is pivotallyr connected to a link 2T which in turn is connected to the wrist pin 28 carriedby the driving member 29 whereby the rotation ofthe driving member will give to the lever 25 an oscillating motion. This motion is transmitted through the block 21 to the bushing 20 and to the loop holder 18. y

'lhe loop holder 18 is bifurcated at its forward end, thus leaving a central opening into which one side of a loop of thread may pass. 'l here is a finger 3() on the outer side of the end opening and a finger or prong 81 extends in the reverse direction from the finger El() from the opposite side of the hifureated holder and it extends at an angle toward the finger 3() approaching that finleo' ger closely near its base and overlappingit slightly. By this construction it will be observed that a thread pulled back in between the lingers and 31 will be guided down to the point where the end of finger 314overlies the finger 30 and will pass through the small opening here left in behind the finger 31. Since the finger 31 overlaps finger 30, if the thread is now pulled in the reverse direction it will ride up the prong or finger 31 and will therefore be moved out of position or to one side of the position whichy it previously occupied when it was engaged by the finger 30. When, therefore, one side of a loop moves down the finger 30 and behind the finger 31 and those parts are moved in the reverse direction, the loop` will be spread, one side passing up the inner side of the finger 31 and the other side of the loop vpassing along the outer side of the finger 30. This is illustrated in Fig. 5 where the needle is shown as entering -between the two fingers just as the loop is spread so that the new loop formed by the needle will pass through the previously formed loop. In order to prevent the thread from becoming accidentally disengaged on the finger 31, l preferably place a light spring 32 Within the bifurcated end of the holder 18, bearing on the inner face of the finger 31 between its ends and this spring furnishes a slight resistance to the passage of the thread having a rounded end for that purpose. The holder 18 is curved substantially on an are of a circle with the center of the shaft 15 as its center. `When the needle is descending, as shown in Fig. 5, the holder 18 is moving backward or to the right as shown and thus when the needle has entered through the loop 33 the loopV is being moved to the left so that it will fall from the end of finger 30 and be retained only by the finger 31. At this time the loop 3-1 which is formed by the needle is' engaged by the rotary hook 16 and isin turn spread and carried around as shown in Fig. 7 so that when itis drawn up it will engage the finger 30, as shown in Flg. 8 and at the same time the preceding loop 33 is drawn up tight against the clothl to complete the stitch. As seen in Fig. 6 when the loop 34 is being engaged by the hook 16 the preceding loop 33 has been moved to one side by the finger 31 so that it is out of the path of the hooklG and can not bev accidentally engaged by it. When the loop 33 is o n the nger 31, as shown in Fig. 6, and the holder 18 is so turned as to move forward, as shown in Figs. 7 and 8, the loop 33 moves back down the finger 31 to its end and is permitted to freely escape under the action of the take-up. This release of the loop is brought about by the movement of the holder and is also assisted by the curved form of that holder which makes the finger 31 occupy an upwardlyinclined position to the machine as a lock stitch machine.

acconti ward its point when the loop is being drawn i ofi by the take-up. It will be observed that the hook 16 makes two revolutions while the holder 18 makes one reeiprocation and therefore it is in this type of device necessary to hold the loop 33 in a position Where it will not be engaged by the hook in its idle revolution or in the revolution in which it engages the succeeding loop. j

In Figs. 1, 2 and 3, I have shown means for throwing into and out of operation the loop holder18 which causes the cha-in stitch. When this holder is out of operation at the outer end of its stroke, it does not interfere in any way with the ordinary operation of When the machine is used as a lock stitch machine v thread is of course placed in the bobbin carried within the rotary hook 16 and that thread is by the usual operation interlocked with the upper thread, but when the device is used as a chain'stitch machine, the lower thread can be taken out or simply cut so that only the upper thread will be used. The tension and other adjustments of the vmachine remain exactly the same and it is not even necessary to cut or remove the lower thread, but if it-is notent, it will be caught upl and interlocked with the chain stitch showing an extra amount of thread on the under surface of the seam.

The driving member 29 has a circumferentialgroove 35 in which fits the forked lever 36 extending about half way around the member and this forked lever has two purposes. It holds the-driving member 29 in position on theshaft 12, which extends down below the bevel gear 13 and it also serves to act as a stop for pins 37 carried by the clutch block 38. The pins on the clutch block 38 pass longitudinally into the drive member 29 out near the margin entering the groove 35. There are two of these pins on opposite sides and the forked member 36 prevents them from entering the groove until those pins occup a single position where each will be imme iately ahead of the ends of the forked lever 36. The pins' 37 are always in engagement with the drive member 35 so that the clutch block and'drive member `always rotate together. These pins furthermore project from the opposite side of the clutch block and enter two holes in the fixed block 39 secured to the shaft 12 below the bevel gear 13. When the pins are in engagement with the block 39, the shaft 12'will drive the drive member 29, thereby operating the loop holder 18. as previously described. Theends of t-he forked lever 86 are in such position that the clutch block 38 can `not be moved out of engagement with the block 3f) except when the loop holder 18 is at the outer limit of its rearward movement and is out of the path of the needle. This arrangement makes it certain that the change from the chain stitch to the lock stitch will not be made while the loop holder is in the way of the needle and it furthermore locks the loop holder out of the way and prevents it from accidentally getting in the path of the needle. Since there are only two holes in the fixed block 39, it will also be apparent that when the clutch is out of engagement with that block it can be brought into engagement only in one position. For this purpose the pins 3T could be placed exactly opposite and the holes in which they fit should of course have the same arrangement. This will insure that when the change is made from the lock stitch to the chain stitch the loop holder will be thrown into operation at exactly the right instant in the cycle of operation of the stitch forming mechanism.

In Figs. l and 3 I have shown means for engaging and disengaging 'the clutch block 38 easily accessible to the operator of the machine. This means includes a bell crank pivotally supported on the main frame of the machine at 40 and having two arms 4l extending on opposite sides ot the clutch block. Pins 42 extend toward each other on the ends of arms 41 entering the circumferential groove 43 in the clutch block. rThe other arm of the bell crank extends out through a short upwardly extending slot 44 neai 'the base ot the column 2 and a thumb nut 45 has screw threaded connection with the end of said arm lfor clamping it in either adjusted position in said slot. In order to change from the lock stitch to the chain stitch, the operator loosens the nut 45 and presses it downward while turning the machine and when the fixed block 39 reaches the position in its rotation where the openings therein register with the upper ends of the pins 37, the clutch block will move upward under the infiuence of the downward pressure on nut 45 and the pins will enter the openings locking theiixed member 39 to the driving member 29 whereby they will rotate together. The thumb nut is then tightened to hold the bell crank in place.

It will be understood that my invention is not limited to the exact details of construction and that modifications may be made in many respects without departing from the main principles of my invention.

Having described .my invention what l claim and desire `to secure by Letters-Patent is,

l. The combination with stitch formingr mechanism includin a needle and a rotary hook, of a loop hol ing member adapted to enter the loop above said rotary hook, means formoving said member forward and backward, fiingers on said member adapted to spread the loop to permit the needle to enter through it and for moving said loop to one side out of the path of the hook during the succeeding revolution, and means for taking up the first mentioned loop as the succeeding loop is drawn up.

2. The combination with stitch forming mechanism including a needle and a rotary hook, of a loop holding member adapted to enter the loop above said rotary hook, means for moving said .member forward and backward, fingers on said member adapted to spread the loop to permit the needle to enter through it as the member is moved backward and to hold said loop to one side out of the path of the hook during the greater portion ot' the succeeding revolution, and means for taking up the first loop as the succeeding loop is drawn up across said fingers.

The combination with stitch forming mechanism including a needle and a rotary hook, of a loop holding member adapted to enter the loop above said rotary hook, means for reciprocating said member,y means for drawing said loop iip around said member when the member moves forward, means on said member for shifting the loop to one side when said member moves backward and for releasing it when the member again moves forward.

4.- The combination with stitch forming mechanism including a needle and a rotary hook, ot a loop holding member adapted to. enter the loop above said rotary hook, means for reciprocating said member, means for drawing said loop` up around said member when the member moves forward, and means on said member for spreading said loop to permit the needle to pass down through it as the member moves backward and for moving said loop to one side out of the way when the needle is withdrawn and for releasing said loop when tlie member again moves forward.

5. The combination with stitch forming mechanism including a needle and a rotary hook, of a loop holding member having two fingers, means for reci rocating said member to cause one of said ngers on the forward movement to enter the loop carried around by said hook, means for drawing said loop up around said finger, said fingers being so related that the second finger will enter and spread saidloop during the backward movement, transferrin it to the second linger on the completion o said backward movement and releasing it on the next forward movement, and means for passing the needle down through said loop when spread between said fingers.

6. In a sewing machine, the combination with a work-plate of a needle adapted to pass down through said plate and nieans for operating said needle, means below said plate for engaging' and spreading the loop of thread carried by said needle, a loop holder above said loop engaging means, two

fingers on said holder, means for moving said holder forward to make one finger enter the spread loop, and for moving it backward, the fingers being so related that on the backward movement the loop will be engaged by the second finger and spread and then transferred to the second nger and on the next forward movement will be released, and means for passing the needle down through the loop when spread by said fingers to form a second loop.

7 In a sewing machine, the 'combination with a work-plate, of a needle adapted to pass down through said plate and means for operating said needle, means below said plate for engaging and spreading the loop of thread carried by said needle, a loop holding finger, means for moving said finger over saidloop engaging means to enter the spread loop, means for drawing up the loop around -said finger, a second finger adapted to enter and spread the loop engaging said first finger, means for passing the needle down through the loop spread between said fingers, and means for so moving the parts as to transfer the loop entirely to the second finger and for then releasing the loop.

8. In a sewing machine, the combination with a work-plate, of a needle adapted to pass down through s-aid plate and means for operating said needle, means below said plate for engaging and spreading the loop of thread carried by said needle, a loop holder above said loop engaging means, twov fingers on said holder arranged at an angle to each other and extending in opposite directions to each other, the free point ofone finger terminating near the base of the other finger allowing room for the passage of a thread between them, means for moving said holder forward, the outer free finger entering the spread loop, one side of the loop passing -in between the two fingers past the end of the second finger, means for moving the holder backward whereby the loop will be caught by thel end 'of the second linger and will be spread and as the backward movement is completed will pass off the end of the first finger and be held to one side by the second finger, and means for passing the .needle down through the loop spread be.- v tween said fingers.

9. A loop holder for chain stitch sewing comprising an outer linger adapted to enter a loop of thread, and a second finger extendfk ing in the reverse direction from a point toward the end of said outer finger inwardly at an angle to its free end in close proximity to the outer finger near its base leaving room -for the Ypassage. of a thread, the relation of said end and base being suoli that when a thread which has entered between them is pulled in the reverse direction it will be en` gaged by and ride along the second finger.

10. A loop holder for chain stitch sewing comprising an outer finger adapted to enter a loop of thread, and a second finger extending in the reverse direction from a point toward the end of said outer finger inwardly at an angle to its free end slightly overlapping said outer finger near its base leaving a space for the passage of a thread pulled up between said fingers.

l1. A loop holder for chain stitchsewing comprising an outer finger adapted to enter a loop of thread, and a second nger ex tending in the reverse direction from a point toward the end of said outer finger inwardly at an angle to its free end slightly overlapping said outer finger near its v.base leaving a space for the passage of a thread pulled up between said fingers, and a light spring bearing against the inner face of said second finger between its ends to offer a slight resistance to thread pulled along said finger.

l2. A loop holder for chain stitch sewing comprising an arm bifurcated at its Outer end having an outer finger adapted to enter` a loop of thread and a finger or prong eX- tending rearwardly from the inner member of the bifurcated end at an angle to and slightly overlapping said outer rfinger near the basey of said bifurcation leaving -rooni for the passage'of a thread past said end.

13. A loop holder for chain stitch sewing comprising an arm bifurcated at its outer end having an outer finger adapted to enter a loop of thread and a finger or prong ex* tending rearwardly from the inner member of the bifurcated end at an angle to and slightly overlapping said outer finger near the base of said bifurcation leavin room for the. passage of a thread past said end, and a light spring secured in the base of said bifurcation and bearing. on the inner side of dssaid second linger or prong between its en 14. In a sewing machine, the combination with the worlnplate, of a needle adapted to pass through said plate carrying a loop of thread, rotary means below-said plate for engaging and spreading said loop, an arm` adapted to rock on a ivot, and a loop holder `carried by said rocking arm comprising an.

arm curved on substantially the arc of a circle and adapted to reciprocate above said rotary spreading means, said last mentioned arm comprising an outer finger adapted to enter a loop of thread, and a second finger,-4

extending inthe reverse direction from a los point toward the endof .said outerv finger inp wardly at an angle to its free end in close proximity to the outer finger near its base leaving` `room for the passage of a thread, the relation of said end and Zbase honig such that when a thread which" has entered between them is pulled init-he, reverse direc@ tion it will be .engaged by and ride alongthe second finger.

15.' In a sewingmachine, the''combination with the work-plate. of a needle adapted t0 pass through said plate carrylng a loop of thread, rotary means below said plate for engaging and spreading said loop, a rotary sha't carrying said loop spreading means, au arm pivoted concentrically of said shaft at the rear of said loop spreading means, a loop holder carried by said arm and projecting over said loop spreading means curved concentrically of said shaft, the said loop holder adapted to hold and spread the loop and to permit the needle to pass through it with the succeeding loop, and an oscillating lever for rocking said arm carrying the loop holder.

16. In a sewing machine, the combination withv the work-plate, of a needle adapted to pass through said plate carrying a loop of thread, rotary means below said plate for engaging and spreading said loop, a rotary shaft carrying said loop spreading means, an arm pivoted eoncentrically of said shaft at the rear of said loop spreading means, a loop holder carried by said arm and projecting over said loop spreading means curved concentrically of said shaft, the said loop holder adapted to hold and spread the loop and to permit the needle to pass through it with the succeeding loop, an oscillating lever for rocking said arm carrying the loop holder, and means for rendering said oscillating lever inoperative.

17. In a sewing machine, the combination with the work-plate. of a needle adapted to pass through said plate carrying a loop of thread, a rotary hook below said plate for engaging and spreading the loop of thread, means for driving said hook two revolutions during each reciprocation of the needle, a loop holder above said hook, means for reciprocating said holder on each alternate revolution of the hook, and means on said holder for engaging the loop on the forward movement, and for spreading the loop to permit the needle to pass through ,it and for moving said loop to one side on the reverse movement and for releasing the loop o n the next forward movement.

18. In a 'sewing machine, the combination with the work-plate, the needle bar head and supporting column, of a rotary shaft below said plate carrying a loop spreader, an upright shaft in said column geared to said rotary shaft, a loop holder adapted t0 oscillate above said spreader, a pivoted lever below said plate adapted to rock said holder, a member driven by said upright shaft for rocking said lever, and a releasable clutch connecting said member in drivingr relation to said upright shaft.

19, In a sewing machine, the combination with the work-plate, the needle bar head and supporting column, of a rotary shaft below said plate carrying a loop spreader, an upright shaft in said column geared to said rotary shaft, a loop holder 'adapted to oscillate from a position above said spreader to an outer position at one side, a. pivoted lever below said plate adapted to rock said holder, a member driven by said upright shaft for rocking said lever, a releasable clutch connecting said member in driving relation to said upright shaft, and means for preventing the disengagement of said clutch except when the loop holder is at its outer posit-ion in its oscillating movement.

20. In a sewing machine, the combination with the work-plate, the needle bar head and supporting column, of a rotary shaft below said plate carrying a loop spreader', an upright shaft in said column geared to said rotary shaft, a loop holder adapted to oscillate from a position above said spreader to an outer position at one side, a pivoted lever below said plate adapted to rock said holder, a-member driven bylsaid upright shaft for rocking said lever, a releasable clutch connecting said member in driving relation to said upright shaft, and means for preventing the engagement or disengagement of said clutch except when the loop holder is at its outer position in its oscillating movement out of the path of the needle.

21.. In a sewing machine, the combination with the work-plate, the needle bar head and supporting column, of means below said plate for spreading a loop of thread, means for driving the needle bar and spreading means, a loop holder adapted to reciprocate from a position above said spreading meansto an outer position at one side, a driving member adapted to operate said holder, a releasable clutch for operatively connecting said driving means to said driving member and means preventing the shifting of said clutch except when said holder is at its outer position of its reciprocation out of the path of the needle.

22. In a sewing machine, the combination with a lock stitch forming mechanism and its driving shaft, of a chain stitch attachment comprising a loop holder adapted to reciprocate into and out of the path of the stitch forming mechanism to engage and disengage the loop of upper thread formed by said mechanism, a driving member for operating said holder, clutch mechanism under the control of the operator for operatively connecting said driving member to saiddriving shaft, and means preventing the shifting o f said clutch mechanism except when said holder is at its outer position out of the path of the needle.

23. In a sewing machine, the combination with a'lock stitch forming mechanism and its driving shaft, of a chain stitch attach\ ment comprising a loop holder adapted to reciprocate into and out of the path of the stitch forming mechanism to engage and disengage the loop of upper thread formed by' said mechanism, a driving member for' operating said holder, mounted concentric with said shaft but free to turn in reference thereto, av fixed block secured to said shaft, a movable clutch block between said fixed block and driving member and connected with said driving member to turn therewith means on the faces of said `clutch block and fixed block for locking them together when in engagement, and means for preventing the movementJ of said' clutch block into or out of engagement with said fixed block except when the loop holder is at the outer position.

24. In a sewing machine, the combination with a lock stitch forming mechanism and its driving shaft, of a chain stitch attachment comprising a loop holder adapted to reciprocate into and out of the path of the stitch forming mechanism to engage and `disengage the loop of upper thread formed by said mechanism, a driving member for operating said holder mounted concentric with said. shaft but .free to turn in reference thereto, a fixed block secured to said shaft, a movable clutch block between said lfixed block and driving member, projections on said clutch block extending into said driving member to make them rotate together, projections on the opposite face of the clutch block adapted to enter openings in said fixed block to lock said block to the driving memv ber, means for shifting said clutch block, and means for preventing such shifting exmedial cept when the loop holder is in its outerl its driving shaft carrying a fixed block near its end, of a chain vstitch attachment comprising a loop holder adapted to reciprocate to engage and disengage the loop of upper thread formed by said mechanism, a driving member for operating said holder mounted concentric with said shaft but free to turn in reference thereto, the said member having a groove in its circumference, a fixed forked arm fitting within said groove and extending part way around said member, a movable clutch block mounted between said fixed block and-driving member, pins passing longitudinally through said clutch block .entering openings in said driving member leading into said groove whereby the block and driving member always turn together and on the opposite side adapted to lenter openings in said fixed blockto lock itto the driving member, the forked arm lying in the Igroove in the path of the pins being so arranged that the clutch block can be moved out of engagement with the fixed block in only one position.

In testimony whereof Iafiix my signature in presence of two witnesses.

RICHARD K. HOHMANN. `Witnessesz ARTHUR L. BRYANT, LoU H. CADARR. 

